超高温多孔陶瓷的制备、性能及应用研究进展

Preparation,Properties and Application of Ultra⁃high Temperature Porous Ceramics:a Review

超高温多孔陶瓷既有超高温陶瓷耐高温、抗氧化/烧蚀、无固态相变的优异特性,又有多孔陶瓷体积密度小、导热系数低的优点,有望成为极端环境下高温隔热、高温腐蚀性气体过滤及高温太阳能吸收等应用的候选材料。按成孔原理的不同,超高温多孔陶瓷的制备方法有部分烧结法、模板复制法、牺牲模板法、冷冻浇注法、直接发泡法和溶胶⁃凝胶法。用部分烧结法制得的超高温多孔陶瓷力学性能优异,但气孔率低且孔结构难以控制;模板复制法制得的陶瓷材料气孔率高,但其气孔结构取决于模板的气孔结构,可设计性较差;牺牲模板法制得的陶瓷材料气孔大小和形貌可控,但气孔分布均匀性差;冷冻浇注法具有高效、低成本等优点,制得的陶瓷材料气孔率高,但用有机溶剂为冷冻介质时,对环境有危害;直接发泡法制得的陶瓷材料气孔率高,孔结构缺陷少,但发泡过程难以控制,对工艺要求较高;溶胶⁃凝胶法制备的陶瓷材料气孔率高,导热系数低,但强度低,且制备成本较高。本文介绍了超高温多孔陶瓷材料的制备方法、性能及应用前景,总结了超高温多孔陶瓷制备方法的优缺点,分析了超高温多孔陶瓷材料面临的问题并展望其前景,以期为制备超高温多孔陶瓷材料提供参考。

Ultra⁃high temperature porous ceramics(UHTCs)exhibited a fascinating combination of properties of porous ceramics including high porosity,high specific surface area,as well as beyond satisfactory physicochemical and high⁃temperature stability and properties of UHTCs including good high temperature volume stability,outstanding oxidation/ablation resistance,which make it as an appropriate candidate for applications under severe environments,such as high⁃temperature thermal insulation components,high⁃temperature hostile gases filtration,high⁃temperature solar absorptions,etc.Ultra⁃high temperature porous ceramics have been fabricated by partial sintering,replica,sacrificial template,freeze casting,direct foaming and sol⁃gel method,based on the different pore⁃forming mechanism.The ultra⁃high temperature porous ceramics prepared by partial sintering method had excellent mechanical properties,but its porosity was low,and pore structure was non⁃uniform.Because the pore morphology of porous ceramics prepared by replica method was inherited form the pore structure of templates,the porous ceramics had high porosity and poor designability for pore structure.The pore size and microstructure of ceramic materials prepared by sacrificial template method can be tailored,but porous ceramics had non⁃uniform pore size distribution.Porous ceramics prepared by freeze casting,which had emerged as a high⁃efficiency,low⁃cost and high porosity;however,its fabricating process was not environmentally friendly due to organic solvents were used as freezing vehicles.The porous ceramics prepared by direct foaming method possessed high porosity and homogeneous pore structure,but the foaming process in a tailored manner was difficult.The ceramic materials prepared by sol⁃gel method had high porosity,low thermal conductivity,low strength and highcost.In this paper,the preparation,properties and future application of ultra⁃high temperature porous ceramics were comprehensively reviewed.The advantages and disadvantages of the fabrication of porous ceramics were summarized.The problems and outlook of ultra⁃high temperature porous ceramic materials were proposed,which aimed to provide guidance for the preparation of ultra⁃high temperature porous ceramic materials.